Railway braking apparatus



Dec. 10, 1935. D. F. COBOURN 2,023,635

RAILWAY BRAKING APPARATUS Filed Jan. 14, 1955 P I 4 56 {/I P5 57 52 50 7b Sounce of Fluid Pflassure 15 INVENTOR DQ11201 F. Caboanz Y @EW HIS A TTORNE Y Patented Dec. 10, 1935 UNITED STATES eArENT oFFicE Application January 14, 1933, Serial No. 651,697

Claims.

My invention relates to railway braking apparatus, and particularly to braking apparatus of the type comprising wheel-engaging braking bars located beside a track rail, and movable toward and away from the rail into braking and nonbraking positions. More particularly, my invention relates to apparatus of the type described in which the braking bars are arranged to be moved to their braking positions by a fluid pressure operated motor or motors, and to be restored to their non-braking positions by suitable biasing means such as gravity.

One object or" my invention is the provision of means for preventing the valve which controls the admission of fluid pressure to the motor or motors from opening under any conditions unless the valve for exhausting fluid pressure from the motor or motors is then closed.

I will describe one form of apparatus embodying my invention, and will then point out the novel features thereof in claims.

The accompanying drawing is a view, partly diagrammatic and partly cross sectioned, illustrating one form of apparatus embodying my invention.

Referring to the drawing, the reference character i designates one track rail of a stretch of railway track, which track rail, as here shown, is secured to a rail support 2 mounted on an adjacent pair of the usual crossties 3, only one crosstie being visible in the drawing. Associated with the rail i is a car retarder comprising two braking bars A and A located on opposite sides of the rail. Each of these braking bars con prises, as usual, a brake beam 4 and a brake shoe 5.

The braking bars A and A are arranged to be moved toward and away from the rail I through the medium of a lever 6 which is pivotally mounted at one end on a pivot pin 8 carried by the rail support 2, and a lever 'i which is pivotally mounted intermediate its ends on the pivot pin 3. The lever 6 is inclined upwardly and extends away from the rail I and is provided in its upper surface with a groove 5* which receives the braking bar A The one end of the lever i is likewise inclined upwardly and extends away from the rail 5 at the opposite side of the rail from the lever 6, and the other end '5" of the lever is inclined downwardly and extends away from the rail 5 below the lever e. The end i of the lever l is provided in its upper surface with a groove t similar to the groove 6 in the lever t, which groove receives the raking bar A Theparts are so arranged and so proportioned that if the outer or free ends of the levers 6 and l are moved apart, the braking bars will be moved toward the rails into their effective or braking positions. When the braking bars occupy their braking positions, the brake 5 shoes will engage the opposite side faces of a car wheel traversing rail 6, and will retard the speed of the car. The center of gravity of the lever 6 and braking bar A is considerably to the right of the pivot pin 8 so that this lever will 10 normally tend to rotate a clockwise direction about the pivot pin. Similarly, the center of gravity or" the lever l and braking bar A is to the left of the pin 8 so that this lever will normally tend to rotate in a counter-clockwise direction about the pivot pin 3. It will be apparent, therefore, that when no force is applied to the free ends of the levers 6 and i to move them apart, the free ends of these levers will move toward each other, thereby moving the braking 0 bars to their inefiective or non-braking positions in which they are illustrated in the drawing.

The levers t and i are arranged to be moved apart by means of a fluid pressure motor M comprising a cylinder 9 containing a reciprocable 2 piston iii which is attached to the inner end of a piston rod ii. The cylinder 9 is pivotally connected with the free end of the lever B by means of trunnions l2 formed on the side of the cylinder and extending through bifurcations i 3 formed on the lever 6, while the piston rod i l is connected at its free end with the free end 1 of the lever l by means of an adjustable eyebolt Hi and a pivot pin l5. Fluid pressure may be admitted to the cylinder 9 on the upper side of the piston It] through an opening it which is threaded to receive a pipe IT. When fluid pressure is admitted to the cylinder 9 through the pipe H and opening iii, the piston it will be forced downwardly and the cylinder 9 upwardly, 49 thereby separating the levers ii and i, and hence moving the braking bars toward their effective or braking positions It will be obvious that when the braking bars are moved to their braking positions, they will exert a braking force which is proportional to the pressure of the fluid supplied to the cylinder SJ The supply of fluid pressure to the cylinder 9 is controlled by means of two fluid pressure operated poppet valves .18 and 59, which poppet valves, in 50 turn, are controlled by means 01" two pilot valves V and V These pilot valves are similar, and each comprises a valve stem 28 biased to an upper position by means of a spring 2i and provided with a winding 22 and an armature 23. When valve V is energized, valve stem 20 of this valve moves downwardly against the bias exerted by the associated spring 2!, and under these conditions a pipe 25 is connected with a pipe 2'? which is constantly supplied with fluid pressure, usually compressed air, from a suitable source not shown in the drawing. When valve V is deenergized,

however, as shown in the drawing, pipe 25 is then vThe two fluid pressure operated poppet valves 7 I8 and I9 are both located in the same valve body 3|], and associated with each poppet valve is a spring w or le which constantly biases the valve to a closed position. Formed in the valve body 30 above the valve l8, and in axial alignment therewith, is a cylinder 32 containing a reciprocable piston 33- which is operatively connected with the valve :8. The upper end of cylinder 33 is connected with the previously described pipe 25, and it will be apparent, therefore, that when valve V is deenergized so that pipe 25 is connected with atmosphere, spring i8= will hold valve I8 closed and piston 33 in its upper position, but that, when valve V is energized, so that pipe 25 is connected with pipe 2'5, the fluid'pressure which is then supplied to pipe 25 will force piston 33 to its lower position, thus opening valve 18. When valve is is opened, cylinder 9 of motor M'is connected with pipe E's through pipe ii, a chamber 35 formed in valve bodytfi, valve i 8, and a chamer 34 formed in valve body 39; but when this valve is closed, cylinder i is disconnected from pipe 2?,

The valvebody 3B is also formed with a second cylinder 3% containing a reciprocable piston 3'. which is operatively connected with the valve I9, and. the upper side of which is subjected to the pressure in the pipe 28. energized, the fluid pressure which is then sup: plied to pipe 28 forces piston 3'! to its lower position thereby opening valve is, and under these conditions, cylinder 8 of motor M becomes connected with atmosphere through pipe ll, chamber 35, valve is, a chamber 33 formed in valve body 38 and a pipe 39. When valve V is deenergized, however, spring us moves valve is to its closed position and piston S'ito its upper position, thus, disconnecting'cylinder 9 from atmosphere.

It follows from the foregoing that when valve- V is energized, fluid pressure will be supplied to cylinders from pipe Zl, and that, when valve V is energized, cylinder 9 will become connected with atmosphere.

The valves V are controlled in part by a plurality of. pressure responsive devices, each designated by the reference character P with a distinguishing exponent. Referring to the pressure responsive device P i or example, this device com-v prises a Bourdon tube 59 connected with the pipe 23, and subjected to the pressure on the upper side of piston 31. The Bourdon tube 60 controls a contact a i ii which is open at all times except when the pressure pipe 23 isbelow a predetermined pressure, for example, 5 pounds per square inch, which pressure is somewhat below the pressure at which valve re. closes. The pres sure responsive devices P? 1 and P are similar to the pressure responsive device P5,-

When valve V is except that the Bourdon tube 40 or each of these devices is connected with the pipe i l which communicates with the cylinder 9 of motor M. The devices P P iand P are arranged to operate in succession as the pressure in cylinder 9 5 increases. For example, for all pressures below 20 pounds per square inch, contact ilel of each of these devices is closed. If thepressure exceeds 20 pounds per square inch, contact ll-M of device P opens, and, if the pres- 1Q sureexceeds 30 pounds per square inch, contact 4 i-- i E of'pressure responsive device P closes. In similar manner, the pressure responsive devices P and P are adjustedto open their contacts 4l l at 45 and '70 pounds per square 15 inch, respectively, and to close their contacts ll-4 l at 55 and 80 pounds per square inch. Of course, these specific pressures are not essential, but areonly mentioned for purposes or" illustration. 20

The valves V are also controlled by means of a manually operable lever L which, as here shown, is capable of assuming five positions, indicated by dotted lines in the drawing, and designated by the reference characters p to 11 inclusive. The 25 lever L controls a plurality of contacts, each designated by the reference character 42 with a distinguishing exponent corresponding to the positionofthe lever in which the corresponding contact is closed. For example, contact 42 is closed 30 in the 10 position of the lever, contact 42 in the 10 position of the lever, etc.

Lever L'will usually be located at a point remote from the braking apparatus, as in the control cabin of a classification yard car retarder 35 system, and will be connected with thebraking apparatus by means of line wires extending from the control cabin to the braking apparatus.

[is shown in the drawing, lever L occupies its p or o position, which is the position which this 4 lever normally occupies when no cars are to be retarded, and all of the contacts of lever L, with the exception of contact 32 are therefore open. Valve V is deenergized, but valve V is energized over a circuit which passes from a suitable source 4,5 of current here shown as a battery B, through wire 43, contact 42 of lever L, line'wire e l, wire 45, winding 22 of valve V wire it, and line wired! back to battery B. Since valve V is deenergized, valvelS is closed and the supply of 50 fluid pressure to motor M is therefore cut oil, and since valve V is energized, valve i9 is open so that cylinder 8 is connected with atmosphere. The brakingbars are therefore held in their ineffectiveor non-braking positions by gravity. 55 Contact it-M of each of the pressure responsive devices P P and P is closed, while contact ii-4i of pressure responsive device P and contact illli of each of the other pressure responsive devices is open. 60

In explaining the operation of the apparatus as a whole, I will first assume that the operator wishes'to make a comparatively light brake application. To do this, he moves. lever L from its 12 to its 10 position, thereby opening contact 32 of-'-lever-L and closing contact ,2 The opening of contact e2 interrupts the circuit which was previously closed for valve V at this contact, and valve V therefore now becomes deenergized and disconnects pipe 28 from pipe 2? and connects pipe 28 with atmosphere. When pipe 28 becomes connected with atmosphere, the pressure in this pipe and in the upper end of cylinder 36 decreases rapidly, and as soon as the pressure has decreased to a predetermined value, for example,

15 pounds per square inch, spring w closes valve [9 thus disconnecting cylinder 9 from atmosphere. When the pressure in pipe 28 has decreased to 5 pounds per square inch, contact llll of pressure responsive device P becomes closed, and a circuit is then completed for valve V which circuit may be traced from battery B through wire 48, contact 42 of lever L, line wire 49, contact H-Ai of pressure responsive device P wire 55, contact l i i t of pressure responsive device P wire 5!, winding 22 of valve V and line wire 57 back to battery B. Valve V therefore becomes energized and connects pipe 21 with pipe 25, thus causing piston 33 to move downwardly and open valve I8. As was previously pointed out, when valve I8 is opened, pipe 21' becomes connected with pipe ll, and fluid at full line pressure is therefore now supplied to cylinder 9 to move the braking bars to their braking positions. As soon as the fluid in the upper end of cylinder 9 reaches 20 pounds per square inch, contact ll- W of pressure responsive device P opens and interrupts the circuit just traced for valve V Valve V then becomes deenergized, thus causing valve is to become closed and hence cutting ofi the supply of fluid pressure to the upper end of cylinder 9. Valve V will now remain deenergized until the pressure in cylinder 9 again decreases below 20 pounds per square inch, at which time contact ii-Al of pressure responsive device P will reclose and reestablish the circuit for valve V Valve [8 will then again become opened and readmit fluid to cylinder 9. If the fluid in cylinder 9 now increases to a pressure of 30 pounds per square inch for any reason, contact 4|4! of pressure responsive device P will become closed and will complete another circuit for valve V this circuit passing from battery B through wire 43, contact 42 of lever L, line wire 49, contact ll-41 of pressure responsive device P an asymmetric unit R in its low resistance direction, wire 45, winding 22 of valve V wire 45, and line wire 4'! back to battery B. Valve V will therefore now become energized and will cause valve l9 to open, thus venting fluid from cylinder 9. Valve ill will continue to vent fluid from cylinder 9 until the pressure in cylinder 9 has decreased to 30 pounds per square inch at which time contact ll- H of pressure responsive device 1 will open and will deenergize valve V When valve V becomes deenergized, valve l9 will reclose and prevent further escape of fluid from cylinder 9. i rthermore, shortly after valve l9 has closed, contact 5l 3l of pressure responsive device P which contact became opened when valve V became energized, will again become closed, so that if the pressure in cylinder 9 again decreases to the value at which contact 3|4i of pressure responsive device P closes, the circuit for valve V will be reestablished. It will be seen, therefore, that when lever L occupies its p position, the braking bars will be held in their braking positions by a pressure of between 20 and 30 pounds per square inch.

If the operator desires to make a more powerful brake application, he moves lever L to its 32 position in which contact 42 is closed. Under these conditions, valve V will be deenergized, and valve V will become energized over a circuit which passes from battery B through wires 53 and 52, contact 42 of lever L, line wire 53, contact H- il of pressure responsive device P wires 54 and 58, contact li5i of pressure res'ponsive device P wire 58, winding 22 of valve V and line wire 41 back to battery B. Fliud pressure will therefore now be admitted to the upper end of cylinder 5 until the pressure of the fluid in the cylinder increases to 45 pounds per square inch, at which pressure contact l!4i of pressure responsive device P4545 will open and will deenergize valve V If the pressure in the upper end of cylinder 9 now increases to 55 pounds per square inch, contact 4i--4l of pressure responsive device 1 will become closed and 10 z will complete another circuit for valve V this latter circuit passing from battery B through wires 58 and 52, contact 42 of lever L, line wire 53, contact M4l of pressure responsive device P asymmetric unit R in its low resistance 15 f direction, wire 45, winding 22 of valve V wire 45. and line wire 47 back to battery B. The resultant energization of valve V will cause valve 99 to open, thus exhausting fluid from cylinder 9 in a manner which will be readily understood g0 from the foregoing description. Valve V will now remain energized until the pressure of the fluid in cylinder 9 has decreased below 55 pounds per square inch at which time contact ll-M of pressure responsive device 1 will open and 25 will interrupt the circuit for valve V Valve 19 will then reclose and after this valve has closed, contact lkil of pressure responsive device P will close. It will be apparent, therefore, that when lever L occupies its 17 position, the braking 30' bars will be held in their braking positions by a pressure of between 45 and 55 pounds per square inch.

If the operator moves lever L to its p position,

valve V will become energized over a circuit which 85 passes from battery 3 through wires 48, 52, and 55, contact 42 of lever L, line wire 5?, contact i4l of pressure responsive device F wires. 58, 54, and 55, contact 4 !ii of pressure responsive device P wire 5!, winding 22 of valve V 40 and wire 41 back to battery B. Under these conditions, fluid will be supplied to the upper end of cylinder 9 until the pressure in the cylinder reaches 70 pounds per square inch, which is the pressure at which contact Ailll of pressure re- 45 sponsive device P opens. If the pressure in cylinder 9 now increases to pounds per square inch, contact il ii of pressure responsive device P will become closed and will complete still another circuit for valve V This latter cir- 60 cuit for valve V may be traced from battery B through wires 48, 52, and 55, contact 32 of lever L, line wire 51, contact itli of pressure responsive device P' asymmetric unit R in its low resistance direction, Wire 55, winding 22 of 55 valve V Wire 56, and line wire 3? back to battery B. Valve V will therefore become energized and cause valve iii to open until the pressure in the upper end of cylinder 9 again decreases to 80 pounds per square inch. When valve V be- 60 comes energized, contact il-M of pressure responsive device P of course, becomes opened and remains opened until valve [5 has closed following the deenergization of valve V It will be seen, therefore, that when lever L is moved to its 6 p position, cylinder 5 is supplied with fluid at a pressure of between 50 and 80 pounds per square inch, and the braking bars therefore exert a corresponding braking force.

If the operator desires to cause the braking bars 70 to exert their maximum braking force, he moves lever L to its p position. Under these conditions, valve V becomes energized and subsequently re mains energized over a circuit which passes from a battery C, through line wire 41, winding 22 of 75 valvev wire contact ib-fil of pressure re' j sponsive'device P wires 56, 54, and 58, an asymmetric unit S in its low resistance direction, line wire 51, contact 42 of lever L, and wire 59 back iito battery C. The energization of valve V of course, causes valve [8 to open, and when valve l8 becomes opened, fluid at full line pressure is supplied to the upper end of cylinder 9. It will be apparent, therefore, that under these condi- :tions, the braking bars are held in their braking positions by fluid at full line pressure.

It should be observed that if the operator moves lever L from a position corresponding to a higher braking force to a position corresponding to a Elower braking force, the apparatus will immediately and automatically reduce the braking pressure to a value corresponding to the new position of the lever in a manner which will be apparent from the drawing without tracing the sequence of operation in detail.

When lever L occupies any position but its 10 position ,so that the braking bars occupy their braking positions, and the operator wishes to restore the braking bars to their non-braking positions in which they are illustrated in the drawing, he restores lever L to its p or off position. When he does this, all circuits previously traced for valve V are interrupted, and the circuit previously traced for valve V including contact M 30 of lever L becomes closed. Valve V therefore becomes deenergized and valve V becomes energized, thus causing valve is to close and valve I!) to open. As a result, the supply of fluid pressure to the upper endof cylinder 9 is cut off, and the 35 'fluid which was previously supplied to the cylinder is vented to atmosphere. The braking bars will therefore move, under the influence of gravity, to their ineffective or non-braking positions. When the fluid has been completely vented from 7 cylinder ii, the contacts l-l of the pressure responsive devices 1 P4545 and P- will all'be closed and the contacts ll-Al of these pressure responsive devices will all be open. Furthermore, since valve V is now energized, contact 4IM of pressure responsive device P will be opened. As a result, when the braking 'bars' reach their non-braking position, all parts. will be restored to the positions in which they are shown in the drawing. 50 It should be particularly pointed out that with the apparatus constructed as shown in the drawing, it is impossible under any conditions for valve V to become energized unless contact 4 l4l of pressure responsive device P is closed, 55 and contact l|4-l will not become closed unless the pressure in pipe 28 is below the pressure at which valve [9 becomes closed. It follows that under no conditions will valve l8 become opened while valve [9 is open, and as a result, there can 60 be no loss of fluid due to fluid flowing from pipe 2'5 through chamber 34, valve l8,chamber 35,

valve i9, chamber 33, and pipe 39 to atmosphere.-

Although I have herein shown and described only one form of railway braking apparatus em- 65 bodying my invention, it is understood that various changes and modifications may be made controlling the exhaust of fluid pressure from said device, an electrical contact which becomes opened whenever said second valve becomesopened and which when once opened remains opened until after said second valve again be- 5:.

comes closed, means for controlling the supply of fluid pressure to said second valve, and means including said contact for controlling the supply of fluid pressure to said first valve.

2. In combination, a fluid pressure operated l0 device, two fluid pressure operated valves for controlling the supply of fluid pressure to, and exhaust of fluid pressure from, said device, means for supplying fluid pressure to one of said valves,

an electrical contact responsive to the pressure 15 of the fluid supplied to said one valve and arranged to open at a predetermined pressure, and means controlled by said contact for controlling the supply of fluid pressure to the other valve.

3. In combination, a fluid pressure operated 20 device, two fluid pressure operated valves, one for controlling the supply of fluid pressure to, and the other for controlling the exhaust of fluid pressure from, said device, means for controlling the supply of fluid pressure to said other valve, 25 1 and electrically operated means responsive to the pressure of the fluid supplied to said other valve for controlling the supply of fluid pressure to said one valve.

l. Railway braking apparatus comprising two} braking bars movable toward and away from a track rail into braking and non-braking positions and biased to a non-braking position, a fluid pressure motor for moving said braking bars to their braking positions, a first fluid pressure operated valve for controlling the admission of fluid pressure to said motor, a second fluid pressure operated valve for controlling the exhaust of fluid pressure from said motor, a first electropneumatic pilot valve for controlling the supply of fluid pressure to said first fluid pressure operated valve, a second electropneumatic pilot valve for controlling the supply of fluid pressure to said second fluid pressure operated valve, a contact, means responsive to the pressure of the fluid supplied to said second fluid pressure operated valve for operating said contact, said means being so adjusted that said contact will become opened whenever said second valve becomes opened and will remain open until after said scond valve has subsequently become closed, a manually operable lever, a circuit for said second electropneumatic valve controlled by said levenand a circuit for said first electropneumatic valve controlled by said lever and including said contact.

5. Railway braking apparatus comprising two braking bars movable toward and away from the track railsinto braking and non-braking positions and biased to abraking position, a fluid pressure motor for moving said braking bars to their braking positions, a first fluid pressure operated valve for controlling the exhaust of fluid pressure from said motor, "manually controlled means for at times supplying fluid pressure to said valve to open said valve, a contact responsive to the pressure of the fluid supplied to said valve and arranged to become opened whenever said valve becomes opened and to subsequently remain open until after said valve again becomes closed, and means controlled in part by said contact for controlling the admission of fluid pressure to said motor. 

